The Preview area shows the currently configured MessageBox. Simply change the options and immediately the preview area will show the updated MessageBox and the Generated Code area will show the generated code:

A couple things of note:

You can define a default button by clicking the specific button in the "Buttons and Default Button" section. This is the button that will be pressed if the user clicks Enter when the MessageBox is shown. In the previous two images, the option "No" was selected as the default button.

The MessageBox outputs a value corresponding to the button that the user clicked. In the Generated Code box you can see a Select Case statement is used to handle the different options:

Select Case answer
Case vbYes
Case vbNo
Case vbCancel
End Select

The procedure should perform different actions depending on if Yes, No, or Cancel is selected. To accomplish this, enter the desired actions into the Select Case statement: